This invention relates to security seals of the type wherein a filament is passed into or through a seal body in engagement with a metal locking element located within the body.
Numerous fasteners and seals are known wherein a sheet metal locking member has teeth which engage and grip a filament, shaft or stud inserted there against. For example, U.S. Pat. No. 2,356,856 to Komenak discloses a detection seal including a tie wire, a cup shaped closure member with an opening for receiving the wire, a cover with an opening through which the wire passes and a detent plate with resilient lips. The wire passes between the lips by threading the wire into the device. The lips flex when the wire is pushed between them. The wire can not be removed in the reverse direction as the lips dig into the wire. The detent plate can shift to permit alignment of the holes with the lips. The lips have parallel straight edges and the detent plate has a relatively large surface. However, it appears that the wire could be unthreaded from the locking engagement with the lips in the same manner it was inserted. This unlocking would defeat the seal and is unsatisfactory.
U.S. Pat. No. 2,740,654 to Orschel discloses a cord seal lock wherein a leaf spring engages a cord at a toothed edge of the spring. An attempt to remove the cord results in the leaf spring edge teeth digging into the cord and preventing its removal. However, it appears that the wire may be removed by a threading action which is undesirable.
U.S. Pat. No. 881,407 to Jewett discloses a bag seal comprising a tubular member with inner facing barbs for gripping a cord in the channel of the member.
U.S. Pat. No. 2,140,320 discloses locking tongues formed in a spring plate which engage a U-shaped shackle. The tongues form lips which indent into the softer shackle, the tongues being enclosed in a cup shaped members.
U.S. Pat. No. 2,458,409 discloses an outlet box connector with spring fingers of different lengths for engaging a cable and securing the cable to an electrical box.
U.S. Pat. No. 5,702,076 discloses an insulator for mounting pipe in a metal wall stud. The device has a plurality of pie shaped gripping segments for gripping a pipe. The segments deflect when the pipe is inserted therebetween.
Also, fastening devices, known as Tinnerman fasteners, employ sheet metal nuts having inner edges used to grip threads so that the nut although sheet metal, can lock to the threads as a nut with multiple axially extending threads. Also, cap type fasteners are known, referred to as speed nuts, which slip over a shaft and grip the shaft with deflecting fingers. This device is not used as a seal.
The problem with all of the above arrangements is that the wire, pipe, cord and so on may be twisted free from the locking engagement. This is undesirable in a security seal wherein it is desired that the seal be broken in order to open it so as to provide evidence of tampering. The present invention is a recognition of a need for a low cost seal wherein a wire or filament severs in order to remove it and the wire or filament can not be twisted free.
A seal according to the present invention which overcomes the above noted problems with the prior art seals comprises a filament; a housing defining a first chamber with a first opening having a transverse dimension, the filament for being received in and passing through the opening into the chamber; and a spring metal filament first locking insert captured in the chamber, the insert having a plurality of radially inwardly extending resilient fingers each of a transverse width and terminating at a tip, at least one of the tips tapering to substantially a point, the tips defining a region therebetween smaller than the filament thickness, the filament for being received in the region in a first insertion direction through the opening, the filament for abutting and flexing the tips such that the tips impose a resilient compressive load against the inserted filament, the filament and insert being of relative hardness such that the at least one tip point digs into the received inserted filament in response to withdrawal of the filament from the chamber in a second direction opposite the first insertion direction such that the filament is severed as the filament is withdrawn. As a result, the severed filament provides tampering evidence.
In one aspect, the chamber and the insert are arranged so that the insert rotates in response to rotation of the inserted received filament at least in response to a force on the insert by the inserted filament in the second withdrawal direction. Thus any attempt to remove the filament by twisting is of no effect because the insert will also rotate with the filament. The insert rotates because the tips digging into the filament provide a grip sufficient to permit a torque to be applied to the insert via the tips. In contrast, a flat edge engagement with the filament as in the prior art devices employing straight gripping edges or relatively large radii on the gripping edges can not receive a sufficient rotational torque from the rotating filament as the filament will merely slide against the edge as the filament rotates.
In a further aspect, the insert comprises an annular array of the fingers, a plurality of the fingers of the array each having a tip tapering substantially to a point.
In a further aspect, at least two fingers have nested complementary tips.
In a further aspect, the insert is a circular element and includes an annular array of identical fingers each with a tip tapering to the point.
In a further aspect, all the tips abut each other in a plane.
In a still further aspect, the filament has a transverse thickness and the tips are in close but spaced relationship, which spaced relationship defines a transverse space substantially smaller than the filament thickness.
In a still further aspect, the insert has a flat periphery lying in a plane with the fingers biased out of the plane and having a given thickness, the fingers each being defined by a radial dimension and a dimension transverse the radial direction which transverse dimension is substantially larger than the given thickness.
Preferably, the housing opening has a transverse dimension, further including a support member in the chamber between the housing opening and the insert, the support member having an aperture for receiving the filament therethrough, the aperture having a transverse dimension smaller than the transverse dimension of the housing opening, the support member for precluding bending of the fingers in the second direction in response of a force applied to the received filament in the second direction.
Preferably the at least one finger has a width and a length forming a rectangular member, the tip being at a radially inward end of the length.
In a further aspect, the insert and fingers lie in a plane, the transverse width of the fingers and the thickness thereof being sufficiently great to preclude lateral circumferential twisting of the fingers in the plane in response to rotation of the inserted filament secured thereto.
In a further aspect, a first portion of the fingers has a first length and a second portion of the tips have a second length different than the first length, the tips of all of the fingers abutting and being complementary to each other.
Preferably, the insert is a circular disk and all of the tips mate at the center of the disk in complementary symmetrical pointed fashion. In addition, the insert preferably is flat at the periphery with the fingers biased away from the plane of the periphery and have a given thickness, the fingers each being defined by a radial dimension and a dimension transverse the radial direction which transverse dimension is substantially larger than the given thickness.
In a further aspect, the housing opening has a transverse dimension, the seal further including a support member in the chamber between the housing opening and the insert, the support member having an aperture for receiving the filament therethrough, the aperture having a transverse dimension smaller than the transverse dimension of the housing opening, the support member for precluding bending of the fingers in the second direction in response of a force applied to the received filament in the second direction. Thus, with the support member present, during withdrawal, the tapered tips of the fingers, which fingers are weak, can not be bent in a reverse withdrawal direction so as to permit the filament to be withdrawn from the seal. Preferably, the insert is a hardened spring steel flat disk and the support member is a hardened spring flat steel disk.
In a further aspect, a connecting element hinges a first housing member to a second complementary housing member, the housing being one piece molded thermoplastic.
In a further aspect, the housing includes two complementary housing portions, a first portion has a cavity and a second portion has a male projection located in the cavity, an end of the filament being located in the cavity between the first and second portions, the housing including a rib member in the cavity for locking the filament end to the housing.
In a still further aspect, the filament has first and second end portions, the first end portion being secured to the first insert in the first chamber, the housing having a second chamber and a second opening in communication with the second chamber, further including a second insert identical to the first insert in the second chamber for receiving the second end for selectively locking the second end to the housing. Thus a padlock type seal may be provided in this embodiment.
In this embodiment, each insert is a steel circular disk, each chamber being circular cylindrical and elongated defining a longitudinal axis, each chamber having an annular recess for receiving the corresponding insert, the recess for releasably retaining the corresponding insert axially in the respective chamber.
In a further aspect, the housing comprises a body including first and second portions, the first opening being in the first portion and the second opening being in the second portion, the body including a third portion having the chambers, the first and second portions being coupled to the third portion by weakening means such that the first and second portions will selectively independently sever from the third portion in response to a withdrawal force on the corresponding insert by the filament. Thus in this aspect, the body portions when separated provide tamper evidence rather than a severed filament since in a padlock arrangement the filament may be a solid wire that is difficult to sever.
In a seal having a housing, a locking insert captured in the housing according to a further aspect of the invention comprises a circular cylindrical disk having a plurality of rectangular radially inwardly extending fingers each finger terminating at a tapered pointed tip, the tips being adjacent and complementary; a tip support member having a central aperture aligned with the complementary pointed tips for receiving a filament therethrough; and means for securing the support member to the disk.